Normal Play Time (NPT) is mainly used in an application such as HTML, and indicates a time axis of relative time from the beginning of a specific stream source. In a program-linked application, by using the NPT, regardless of an actual broadcast time, it is possible to describe application operation in which a relative time on a program source (for example, indicated by time from the beginning and not including a Commercial Message (CM)) is specified.
The NPT is realized by intermittently transmitting an Event Message Table (EMT) in which a UTC-NPT reference descriptor is arranged, in a broadcast signal (see Non-Patent Document 1). The UTC-NPT reference descriptor includes mapping information between a pair of a Coordinated Universal Time (UTC) time and a Normal Play Time (NPT) time at the time ahead of reception.
By intermittently acquiring the UTC-NPT reference descriptor, it is possible to perform time conversion from the UTC time to the NPT time, or from the NPT time to the UTC time, at any point in time. Further, as the NPT of a main program, in a case where a Commercial Message (CM) enters the program, even if a UTC time passes, a mechanism is also included that can stop the NPT during that time.
As a use example to an application, it can be considered to set a timer in which a specific NPT time is specified to generate a timer event when the time comes, and start execution of the application. With this configuration, it is possible to produce an application linked in a specific scene in advance, regardless of an actual broadcast time and a CM insertion position.